Manually operated small lubricators, commonly referred to as "grease guns", have found considerable success in the past several decades in the private consumer market frequently for personal automobile lubrication. These lubricators usually include a cylinder with one closed end that acts as a reservoir for grease which is loaded into the cylinder in several ways, one being with a prefilled cartridge and others by bulk loading lubricant directly into the cylinder. The cylinder has an open end that is closed by a dispensing head that has a piston reciprocably mounted therein that forces lubricant under pressure through an outlet fitting usually extending forwardly from the head. The highly viscous lubricant is urged forwardly in the cylinder toward the head by the continuous force of a spring biased follower assembly in the rear of the cylinder that frequently includes an elastomeric follower that actually is a piston having a diameter equal to or somewhat larger than the inside diameter of the cylinder.
This dispensing piston is reciprocated in the head by a lever, frequently constructed of sheet metal, that is pivotally connected to the head by a sheet metal link and also pivotally connected to the end of the piston which projects from the head. The link is necessary to accommodate the crank-like movement of the lever as it reciprocates the piston linearly. The link is usually fastened to both the head and the end of the lever by rivets and the piston is connected to the lever in the same manner.
The head itself is usually constructed of metal and requires machining after casting of the outlet fitting, the cylinder receiving portion, the inlet and outlet passages as well as the main bore in the head that slidably receives the piston.
The intermediate link and the casting and multiple machining operations required to form the head contribute significantly to the cost of the overall grease gun and render the grease gun too expensive for a large segment of consumers.
It is a primary object of the present invention to ameliorate the problems noted above in prior hand held and operated lubrication devices.